#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)

#include "Button.h"
#include "Midi.h"

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

const unsigned long second = 1000000;
const float minute = 60.0;

int bpmPotPin = A1;
int bpmPotVal = 0;
float bpm = 120.0;
float beatsPerSecond = minute / bpm;
float beatLength = beatsPerSecond * second;
float quarterNoteLength = beatLength;
float eightNoteLength = quarterNoteLength / 2;
float sixteenthNoteLength = eightNoteLength / 2;
float clockTickLength = quarterNoteLength / 24;

unsigned long now = 0;
unsigned long nextTick = clockTickLength;

const int buttonPin = 2;
const int ledPin = 13;

int ledState = LOW;
int playState = LOW;

Button recordButton(2);
Button stopButton(11);
Button playButton(6);
Midi midi;

void setup() {
  recordButton.setup();
  stopButton.setup();
  playButton.setup();
  midi.setup();
  
  pinMode(ledPin, OUTPUT);

  digitalWrite(ledPin, ledState);

  // Serial.begin(31250);
  // Serial.begin(115200);
  Serial.begin(9600);

  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { 
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); // Don't proceed, loop forever
  }

  display.display();
  display.clearDisplay();

  display.setTextSize(1);             // Normal 1:1 pixel scale
  display.setTextColor(WHITE);        // Draw white text
  display.setCursor(0,0);             // Start at top-left corner
  display.println(F("Hello, world!"));
  display.display();
}

void setBpm(float newBpm) {
  bpm = newBpm;
  beatsPerSecond = minute / bpm;
  beatLength = beatsPerSecond * second;
  quarterNoteLength = beatLength;
  eightNoteLength = quarterNoteLength / 2;
  sixteenthNoteLength = eightNoteLength / 2;
  clockTickLength = quarterNoteLength / 24;

  display.clearDisplay();
  display.setCursor(0,0);
  display.println(F("BPM:"));
  display.println(bpm);
  display.display();
}

void loop() {
  now = micros();

  if (now >= nextTick) {
    // Serial.write(Midi::CLOCK);
    nextTick = nextTick + clockTickLength;
  }

  bpmPotVal = analogRead(bpmPotPin);

  if (bpmPotVal != bpm) {
    setBpm(bpmPotVal);
  }

  recordButton.update(now);
  stopButton.update(now);
  playButton.update(now);
  midi.update(now);

  if (recordButton.is_pressed() == HIGH) {
    midi.loadNotes();
    midi.sendNotes();
  }

  if (playButton.is_pressed() == HIGH) {
    if (playState == HIGH) {
      Serial.write(Midi::STOP);
      playState = LOW;
    } else {
      Serial.write(Midi::CONT);
      playState = HIGH;
    }
  }

  if (stopButton.is_pressed() == HIGH) {
    if (playState == HIGH) {
      Serial.write(Midi::STOP);
      Serial.write(Midi::START);
    }
  }

  digitalWrite(ledPin, playState);
}